


Blue Prince, Red Knight

by Slinky (Golbez)



Category: Undertale (Video Game)
Genre: Alternate Universe - Canon Divergence, Filipino Frisk, First Child!Frisk, Gen, Illustrated, Multilingual Character, POV Frisk, POV Second Person, Rebooted as comic! Check Notes
Language: English
Status: Completed
Published: 2016-01-22
Updated: 2017-03-24
Packaged: 2018-05-15 12:59:48
Rating: Teen And Up Audiences
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 3
Words: 9,968
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/5786140
Author URL: https://archiveofourown.org/users/Golbez/pseuds/Slinky
Summary: <blockquote class="userstuff">
              <p>Once upon a time, a human child fell to the Underground. Rescued by young Prince Asriel, they were taken in by the royal family and raised as a second child.</p><p>Today, they serve the Underground as Captain Frisk Dreemurr of the Royal Guard. As the first and only human to have ever fallen, they are the future of monsters and humans, bringing hope and mercy to all around them.</p><p>Fic abandoned. <a href="https://bprk-comic.tumblr.com/">Rebooted as a comic.</a></p>
            </blockquote>





	1. Lionheart

**Author's Note:**

> Howdy! Welcome to the beginning of my _big_ AU fic. I spent quite some time developing this AU, and I'm super excited to get this ball rolling.
> 
> On an important note, the version of the Underground in this fic is multilingual. When you come across non-English dialogue, I ask that you don't immediately use a translator on them and simply keep reading and let the text or the characters themselves contextualize/translate it for you.
> 
> This fic also has an RP/Ask blog for Captain Frisk on [mercystick](http://mercystick.tumblr.com/) @ tumblr. I fully encourage asks addressed to any character who shows up in the fic, not just to Captain Frisk.
> 
> That said, here's to the beginning of what I hope will be quite the wild ride.
> 
> (Also please note 03, 04, and Doge are not OC's but enemies cut from the game.)

You've always found the otherworldly light of New Home's garden to be comforting and warm. Combined with the gentle fragrances of the flowers around you and the faint breeze that slips through here and the Barrier room, this one room in the castle has always given you a peace that you might never find anywhere else.

Not to say peace is scarce in your world - far from it. You live a life of peace in a kingdom which, while imprisoned by your kind, has only ever been good to you. You need not fear anything when you traverse the Underground. This is your home, this is the kingdom that has seen you grow. Peace is no scarcer than love, and love is all that the monsters of the Underground have ever shown you.

That, and the garden is simply a lovely place to be in so early in the morning. It is the epitome of tranquility at this hour, before the castle is opened to everyone.

It's nice, to be able to stop and appreciate the flowers every so often like this.

(The golden flowers in particular have always been your favorite.)

But that's enough dallying. Your name is Frisk Dreemurr, and, as Captain of the Royal Guard, you've got work to do.

The smell of butterscotch fills the air as you make your way through your home.

_I'm in search of the Lionheart  
Nobody else but the pure can save me._

You are no harsh taskmaster, but you expect the best from your Guards. Morning pleasantries are had, armor checks done, assignments for the day handed out. All within the hour.

The Guard moves out for the day, but two linger. You catch the end of their conversation as they approach.

"Go on, 03, it's _your_ decision -"

"But Doge, I'm nervous -"

They should already be off on their way, as should you, but It's clear to you that 03 has something important to say, so you wait for both guards to come closer.

" _Magandang umaga_ , Captain," says Doge, and when 03 doesn't say anything, Doge prods at her until she echoes the greeting.

"Good morning, Doge, 03," you return their greeting with a kind smile, looking between them. "Something wrong?"

"Not at all," says Doge, "03's got a favor to ask."

You turn to the guard in question. "What can I do for you?"

03 shakes her head, antennae swaying with the motion, before finally speaking.

"I, um, I was hoping I could request a new partner."

"A new partner?" You look between her and Doge. As far as you were concerned, the pair worked well together, and 03 had learned a lot under the more experienced Doge’s guidance. "Is everything all right between you two?"

"Everything’s fine, Captain." Doge is quick to answer. "We talked this over and decided this is for the best."

03 nods in agreement, so you turn to her again and ask, "Who did you have in mind?"

"I was hoping I could partner with 04."

"You and 04?" You take a moment to consider it. They would not be too bad of a match, and 04 could use someone like 03 at her side. The silence stretches on as you think it over, long enough that 03 steps back and tugs at Doge’s arm for them to leave now.

"This wasn't a good idea," she says.

You step closer, then raise your hand and place it on her arm, the highest you can reach on her. "I'll allow it."

"I mean, Doge and I are already--" She cuts herself off, helm slowly tilting down toward you. You're certain she's staring. "Wait, really?"

"Well, clearly you’ve thought about this and talked this through with Doge," you say, "So I’ll discuss it with 04 tonight and see what she thinks of it."

"Oh." You can't see her face, but the way she clasps her hands together makes you believe she might be smiling. Doge wears a barely contained one herself. 

"Of course," you continue, "if 04 were to disagree to it, there will be nothing I can do."

"Y-yes, of course!"

"But I’m certain she’ll agree to it." You offer her a smile of your own now. "You're a good guard, and I’m sure you'll make a great team with her."

"Oh, _salamat_ Captain!" exclaims 03, and before you can say anything further, she wraps her arms around you and lifts you off the ground. Smells like nervousness.

She sets you back down a moment later. You breathe in deeply and try not to be too obvious in gasping for breath. 03 doesn't seem to notice the effect her hug had, and you'd rather not make her feel like she'd made a mistake.

"You're welcome," you tell her, before gesturing between her and Doge. "Now I do believe you two should be off. It may be your last day as partners, after all."

"Yes Captain!" exclaims 03, stepping back and about to start on her way. She's quickly replaced by Doge, stepping up close to you and gazing at you intently.

You reach over and pet her, the only reward Doge ever asks of you.

"Yes, you’ve been a good Doge."

She barks once, then steps away as well. "Thank you, Captain. This really means a lot to 03."

"You won't be bothered with working alone?"

"I've always been more of a lone wolf." She grins as you frown at her little joke, then she's turning to 03 and you're watching them head off for likely their last day as a team. 

You start off on your way as well, mulling over the work you'd need to do if 04 said yes as you walk. You'll have to draw up new patrol routes for them, and keep an eye on how effective they are as a team. You'd have to check in on Doge too every so often and see how well she’d adjust to working alone again after so long.

You remind yourself you can do all of that later as you pick up your trusty staff.

(Here's to the Mercy Stick. It's been a loyal companion to you for many years.)

Your patrol route today leads you around the outer rim of the Capital, through the old apartments, and into the areas of Hotland nearest to the Capital. There's nothing particularly unusual about this route save for the detour into the Core.

You wonder if you'll see your Uncle Gaster today. He's been even more reclusive than usual as of late and spending all of his time in the Core.

You do one final check of your inventory pouch, and head out. You're barely twenty steps to the castle gate when a hand comes down on your shoulder.

"If it isn't _Kapitan Frisk_!"

You turn, and sure enough, it's your brother. He's the only one who calls you _Kapitan_ , after all.

"And if it isn't _Prinsipe Asriel_." You flourish your hand and bow to him, earning yourself a chuckle. As you straighten yourself, you notice that he's dressed quite formally today, certainly more than needed for a simple outing. "You’re looking sharp today. What's the occasion?"

"Huh?" He glances down at himself before shrugging at you. "Oh right. I’m just finally meeting with the Hotland spiders."

"You’re going alone?" You look him up and down, frowning. "And not even in your armor?"

"I was going to wear it, but mom said it might look like we were afraid of them or didn't trust them."

You sigh and shake your head. That was the sort of thing that you simply do not think much of. All you know is that the spiders are a neutral group running shops all over the Underground, their largest and most influential group being the one in Hotland. You have no doubts that Asriel can take care of himself, but it's your job to worry for him.

"At least take a guard with you."

"That'd fall under ‘afraid of them’ unfortunately."

You shake your head again. This isn't a point you want to concede at all. "I’ll take full responsibility if the spiders decide your guard is an insult."

Before he can say anything, you whip out your phone and fire off a quick message to one of the guards assigned to the castle. In a matter of seconds, a rabbit monster in gray armor comes running up to you.

"Reporting for duty, sir!"

You manage not to wince at their shouting.

"Porin, accompany the Prince to Hotland." You hear Asriel sigh, but ignore him. "Be discreet. I expect a full report later."

"Understood! Sir!" they exclaim, before quickly correcting themselves and lowering their volume. Discreet clearly meant quiet to them, though it wasn't _that_ much quieter. "Pardon, I mean, understood! Sir."

The guard bows, then hurries to Asriel’s side. Your brother gives you a wry look. "I can't believe I forgot how willing you are to pull rank."

"Off on your way now, Prince Asriel," you say, grinning and gesturing toward the gate. "You wouldn't want to make the spiders wait too long."

He rolls his eyes and turns to the guard beside him. "So, Porin, right?" he asks, and when they give him a vigorous nod, he grins and continues, "Are you good at running?"

"I am! I mean, yes, sir, I am."

"Good, keep up now." And with that, Asriel takes off toward the gate. You watch as Porin jolts in surprise, before racing after him. As you step through the gate at a more leisurely pace, you get the feeling that half of Porin’s report will be Asriel’s attempts to ditch them. Unable to bite back a grin, you turn in the opposite direction from them, toward the Capital.

Though peaceful, the Capital is always bustling with life, something that extends even to its outermost edge, where the oldest buildings of the city stand as proud testaments to the monsters of old. As you traverse the uniform streets of the first neighborhood on your patrol route, you greet a number of older monsters, most on their way deeper into the capital, others moving in the same direction as you.

The morning passes by quickly enough. The distinct scents of breakfast _kape_ and _tsa_ fade as the hours pass and you make your way through another neighborhood. Monster children dance around you and play with your cape while you pretend not to notice them. Music drifts by as you walk. Sometimes you stop to address small problems - noisy neighbors, an inner city child separated from her father, pets getting stuck somewhere, that sort of thing.

Eventually, just as various smells signaling the start of the lunch hour begin to waft through the air, you come to the elevator leading down to one of the oldest residences in the Capital, one that also serves as a stopover between Hotland and the Capital.

You expect an empty lobby at this hour. Instead, as the elevator doors open, you're greeted by a cacophony of noise at a volume achievable only by a large group of children.

You stand there for a long moment, surprise plain on your face, as you take in the sight of an unusually large number of children running around the old building’s lobby. It's long enough for the elevator doors to start closing again. You catch the doors with your free hand and quickly hurry over the threshold when they reopen, almost dropping your staff in your rush.

A small white dog scurries past you, entering the elevator. You take a moment to wonder how it’s going to pick a floor.

Turning your attention back to the lobby, you note that none of the children have noticed you yet, so you stand there and survey the room. Most of them are rabbit monsters, and otherwise heavily furred as well. A single adult rabbit monster stands in their midst by the Royal Memorial Fountain, chatting with someone from the Royal Guard. There's no mistaking it: you just walked into a class from Snowdin on a field trip to the Capital.

Wait.

Your gaze trails back to the adult monster. Even with the slight distance and his back turned to you, you can easily identify exactly which of your guardsmen is _not_ on patrol like he's supposed to be at the moment.

You easily maneuver around the groups of children playing, keeping a leisurely pace. As you come up to them, you clear your throat.

"Howdy 01. Making friends?" you say, startling the guard in question. He turns to you stiffly, and you can just _feel_ the uneasiness emanating through his armor.

"Hey, Captain Frisk! You're, like, way early."

"It's around noon," you say, tone flat. He visibly deflates upon hearing that you are in fact right on schedule. You sigh as you gesture behind him with your free hand. "Care to introduce us?"

"Oh! Yeah!" He steps aside, giving you a better look at the rabbit monster. "She's, like, my cousin! And, like, I heard she was bringing her class here for, like, a trip thing so I thought we could, like, catch up and stuff...y’know?"

You count the number of likes he'd used in that sentence alone. Oh, he’s _really_ nervous. You turn away from him and greet his cousin, exchanging pleasantries and simply chatting with her, learning she and her class were waiting for the building’s cafeteria to open. It’s only as you turn back to 01 that you notice his partner standing well behind the fountain, crouched as several children hop off his back.

"Excuse us for a moment," you tell the teacher, before stepping to the side. "01, 02!"

01 hurries to you, blocking sight of his cousin, while 02 straightens himself and shoos away the children around him before coming over to you as well.

"Is this where you were the entire morning?" you ask.

"No way," says 01 quickly, "We were totally on patrol, man. Then we, like, ran into the kids and it was my cuz! Like, I haven’t seen her in years! So then we kinda just, like, hung out with them…"

He trails off. You wait for him to continue, but when he doesn't, you turn to 02 and stare at him expectantly.

"...they're cute kids," is all he offers.

You sigh and shake your head, then look between them. This isn't the sort of thing you expected out of either of them, 02 in particular. You suspect though that he went along with it to make 01 happy.

"01," you say, and he straightens his back and stands at attention. "Let's make this the only time this happens. The next time you have family visiting, let me know and we'll see about giving you some time off. That said, go on, spend the day with your cousin."

"Uh, Captain?"

"You heard me, 01. Go spend the day with your cousin."

"Captain, dude…" And once again, before you can say anything, you find yourself picked up in a crushing hug from one of your heavy armor guards. "Like, that's really nice of you!"

"Hgkk - air -" you manage to say this time, and 02 comes to your rescue, saying something to his partner in that quiet voice of his. 01 quickly drops you and you end up stumbling back against 02.

He catches you easily enough, and much to your chagrin he sets you down like you would a child.

You breath in deeply. 01 looks apologetic, but you say nothing of it further.

"02," you say, turning to him, "Wait for me here while I check in at the Core. We’ll finish your patrol together."

"...sir." Well at least he said something to acknowledge your orders this time.

"I’ll be off now. It was a pleasure meeting your cousin, 01." Without waiting for an answer, you turn and start toward the door directly opposite the Royal Memorial Fountain.

"Yo! Is that Captain Frisk?"

You halt.

An armless monster child in gold and brown stripes comes running by you, skidding to a stop and turning toward you with a jump. You crouch, so you’re eye level with them. Their eyes widen, and a huge grin breaks out onto their face.

"You called?" you ask them, returning the grin. You don't think you've ever seen a child as happy as them in this moment.

"Oh man, oh man, Captain Frisk! Are you catching bad guys?" They're practically bouncing with excitement as they speak. "I'll help you catch them!"

You laugh, before reaching over to pat them on the head. Their eyes widen even further at the contact.

"You're right, I'm about to go catch some bad guys," you tell them, before giving them a grave expression. "But, I have to do this one alone."

"But I can help!" they insist.

You make a point to look around with as serious an expression as you can muster, and you watch as they frown in turn.

"You _can_ help me, but in a different way," you say, then you hold out your staff parallel to the floor, "You see, I’m trying out something new, and I need someone to take care of my staff for me while I'm catching bad guys."

It takes them a moment. "Y-yo, is that the Mercy Stick? Are you really asking me to take care of it?"

You nod, and you're about to hand them the staff when you realize they have no arms for it. They seem to pick up on your hesitation though, so they step forward and position themselves under the staff. You blink as they touch the top of their head to the staff.

You let go. The staff wobbles, and starts to lean over to one side, clearly about to take the child with it. Fearing for their safety, you reach out and grab on again.

Before you can say anything, the child shuffles a little to the right. "Try that again!"

You comply, releasing the staff again. To your amazement, this time it's balanced perfectly on their head.

"This is _so_ cool!" The child hops up and down for a moment, and surprisingly the staff doesn't fall off at all. "I can't believe I'm carrying the Mercy Stick!"

You laugh, then stand and straighten yourself. "I believe you'll do a great job with it. Now then, I should hurry and go catch those bad guys, yes?"

"Yeah!" They turn, the staff swinging around with them, before running off again. You watch them for a moment, as they call out to their friends and quickly find themselves surrounded by other kids.

You can't help but chuckle as you make your way to the door leading to the Core. If you had perhaps one weakness that all the world knew, it’s children. 

When you step through the door though, any lightheartedness in you dies immediately. The noise of the lobby disappears as well, once the door swings shut behind you.

The sound of machinery grows louder as you cross the bridge. There’s something about this place that has always unsettled you, but it is not your place to be afraid of anything.

The doors to the Core part automatically for you. The buzzing of machinery fades as soon as you step through, and you're greeted by the familiar sight of the Core lobby. The elevator before you opens, allowing a handful of monsters dressed in white garb to exit.

They all pause in their chatter to look at you for a moment, before deciding you’re uninteresting to them and moving past you. You hear them pick up their conversations again once behind you, and for a moment the noise of the machinery reaches you, before everything is cut off again by the doors sliding shut.

The Core smells of nothing, not even of the metals composing it or of the monsters who work here. Putting aside your personal distaste of the place, you enter the elevator and have it take you to the control center of the Core.

You're greeted by another monster in white robes, tapping his foot impatiently. "Captain Frisk, you're a little late there." 

"I’ve had an interesting morning," you tell him. It's impossible to tell what he's thinking, considering his face is black and orange stone. You glance around the circular room, noting there are much less monsters at the various monitors right now. "Dr. Gaster isn't here today?"

"Nope," he replies, turning away and reaching for something on the nearest desk. "He's at the lab. Didn't say why. Oh, here's the reports."

He turns back to you with a folder in hand, the summary of the Core’s status for the past week.

You’ve just closed your fingers around it when the ground shakes, and a booming noise thunders through the air.

You freeze, as does the entire room. When no further shaking or noises come, the monster scientists break into a flurry of activity.

"What the hell was _that_?" shouts the one before you, releasing his grip on the folder in favor of scrambling over to one of the other monsters. You barely manage to grab onto the folder without any of the papers slipping out.

"Wasn't us, sir!" announces a monster on the other side of the room. "It's from outside the Core."

Outside the Core…? You spin around and reach for the elevator control, a sinking feeling that the cause is closer than it had seemed. Before you can press anything though, the elevator doors slide open on their own, and a monster in white garb comes running out, slamming against you.

"It exploded! My god…!" they exclaim, and you recognize they're one of the monsters who had exited the Core just moments earlier. You hold onto them, steadying them. The sound of footsteps fills the air as the other monsters come running to your side to peer over your shoulders at their distressed colleague.

"What exploded?" you demand, grip tight on the monster’s arms.

They suck in a breath. "The lab. _Wala na siya_."

Your sinking feeling only gets worse. The Royal Laboratory is gone.


	2. A Past and Future Secret

**Notes for the Chapter:**

> Hi I can't believe how long this took O_O Anyway it's twice as long so, enjoy??

  


_Talking about a past and future secret  
Most of it I don't understand_

This is the sight that had greeted you when you arrived at the Royal Lab: your brother taming and stealing flames from an inferno, feeding them to the fire monsters standing around him. Nearby stood 03 and Doge, and 04 a little ways behind them, each of them coming to greet you before 04 updated you on the situation. You had watched together as the fire diminished while the monsters burned brighter and brighter in turn, until eventually all that remained was the charred and blackened Royal Lab.

And then it was quiet, with the fire monsters shuffling off with the guards. They'd been tossing balls of fire at each other as they went on their way, earning concerned looks from the two guards accompanying them. You'd taken the opportunity to pair up 03 and 04, leaving Doge to stand guard nearby and wait.

You stand beside your brother, looking up at the ruined building, listening as the fire monsters' joking faded into the distance. You glance at each other, before stepping forward through the doorway together.

It reeks of burnt material inside, metal and stone and wood and - other things that you can't identify. Most of the rooms inside are still intact save for their contents. Everywhere you turn are the charred corpses of furniture next to debris, but you can easily identify everything anyway as you move through the rooms together. Here, the stacks of boxes that the scientists never bothered to clear, where you and Asriel pretended to be kings. There, the tables under which the two of you played Monsters and Humans (he played the human). The couch you'd recovered in after a bad allergic reaction, the desks where you'd failed several basic science tests issued by your uncle, the husk of a machine he had used to examine your soul…

You stare at the machine you'd stood under hundreds of times, the flood of memories soured by what you remember to be a tedious and occasionally painful process.

A hand rests on your shoulder, and you look up at your brother. He grimaces, but you shake your head.

"I'm fine," you tell him, "Just need a moment. Go on ahead and see if there's any - any equipment intact."

From the look he gives you, you're sure he understands that you want him to check for more than just equipment.

He nods, and steps onward to one of the doorways ahead. " _Sigaw ka lang_."

"Likewise," you say, telling yourself that it would be okay to shout for him, especially in _this_ place.

You turn back to the machine.

The machine had been broken long before the explosion in some kind of accident that ceased all activity with it, after which Gaster never asked you to stand under it again. Even so, you and Asriel would still come and visit, especially after your lessons and training. You'd watch Gaster and his assistants work, and sometimes you'd accompany them and help with fieldwork that even now you don't really understand.

Lately though, you'd become too busy with your duties to visit often, and even when you saw him at the Core every week, he'd simply shoo you along and get back to work. Then he'd simply stopped leaving his office in the Core, and not even the King or Queen could persuade him otherwise, and now you don't even know if he's been turned to dust or not.

You're drawn out of your thoughts by your brother's voice striking through the still air. He's found someone. You give the machine one long final look before hurrying to the door Asriel had disappeared through.

It's a child. A skeleton child. Despite not being able to see his face, you feel like you've seen him somewhere before, but you aren't sure where.

" - but my brother told me to stay here," the skeleton is saying. Asriel meets your gaze briefly over the child's head, expression rather clearly pleading for your help to convince the child to leave with either of you. Normally he's good with just about anyone, so it's a little surprising that a single child could give him trouble.

"Where's your brother?" you ask from the doorway.

The child whirls about to face you, small dark eyesockets wide with surprise. Then, to your amazement, rather than demanding who you are, he strides over to you with a purposeful gait.

"Sans went back to Gaster's office."

"Okay," you say, crouching to be eye level with him. "This Sans you mentioned - "

"That's my brother. He's really cool." He puffs up, managing to look incredibly self-assured despite the situation. You glance at Asriel, but your brother is frowning and looks to be lost in thought.

"Really really cool?" You let disbelief slip into your tone, raising your eyebrows at him. 

"The _coolest_ ," he replies, looking quite proud of himself.

"Oh, that makes me jealous." You can't hide your grin. "My brother's a nerd who isn't cool at all."

Asriel snorts, loudly. The child doesn't notice, looking rather thoughtful as he mulls over your words. You can only guess what he might be thinking.

"I feel bad for you," he starts, "You might never know how awesome it is to have a super cool brother."

"Never seems a little extreme though," you say. "Maybe with some nudging he can learn to be cool."

"Oh! Maybe I should teach him! Bring me to your brother!" He announces this as if it were the most obvious solution in the world, and you can't help but laugh.

You straighten yourself and gesture to Asriel. "Have at him."

He pauses, gaze following the direction of your hand until he's turning to look at Asriel. He looks back up at you the moment he makes the connection. " _He_ is your brother?"

You smile and nod. The skeleton looks to Asriel again, and seems to scrutinize him for quite a while. You find yourself growing impatient as the silence stretches on. The longer you linger here, the less time you have to look for Gaster.

You reach down, intending to just pick the skeleton up and carry him out if you have to, only for an all too familiar wave of magic to repel your hand. Time seems to slow as you jerk your hand away. You grit your teeth at the pain lancing up your arm. You know this magic. It is the same one that kept you from stepping away from your uncle's machines too quickly, the same one that once danced through these very halls, too strong for even your gloves to nullify.

When you look back up to Asriel, he has a hand outstretched toward you and a grimace upon his face.

The skeleton looks up between the two of you again, clearly oblivious to what had just transpired, before reaching out and grabbing at your brother's outstretched hand. "Let's go! I, Papyrus, am going to show you how to be cool!"

Asriel lurches forward as if stumbling, letting the skeleton - Papyrus - pull him along. You step aside to let them pass by, trying to keep your expression light despite the lingering tingle of magic in your hand. A fairly easy feat, thankfully, with how comical you find the sight of a child who barely reached Asriel's waist leading him around. 

"What about _your_ brother? Didn't he say you should wait here?" asks Asriel. Papyrus stops in his tracks, looking distraught at being reminded of this fact. He looks between Asriel and the wall across you, calling your attention to a black door that, in your memories, led deeper into the lab.

"How about," you say, earning you his gaze, "I go look for Sans and get him? I can explain why you couldn't wait for him." You don't hesitate to volunteer your aid, and when you spot Asriel grin you realize he must have had this in mind all along. What a sneaky brother.

There's that thoughtful look again, until finally Papyrus nods and tugs on Asriel's hand when he steps toward the exit again. "I will trust you with my brother!"

"Thank you for trusting me, Papyrus."

He laughs, a ‘nyeh heh heh' that seems far too cheerful for this place. You watch as Papyrus and Asriel hurry along, the former clearly rather impatient with the latter's leisurely pace. The skeleton was now one less monster to worry about - Asriel would keep him preoccupied while you searched for his brother and for Gaster.

✦ Knowing that Papyrus is safely with Asriel fills you with determination.

You make for the black door across you, and step through into the administrative area of the lab.

It isn't much different here, just more gray walls and gray tiled floor - except somehow unburnt. You imagine your uncle walking through here with documents in his hands, humming to himself while assistants hurried after him. His long stride would have brought him toward his office too quickly for the other scientists to speak to him as they walked, so they would have had to scramble along to keep up. Your uncle, in his infinite levels of _Not Caring_ when it comes to anything uninvolved with science, would have carried on without sparing any of them a single glance. 

You pause outside the door to his office, staring at the name plastered across it. It could be any other day, and you're just visiting uncle Gaster in his office in the lab. Sucking in a breath, you push the door open when you find it unlocked, and stepping through, you're greeted with -

Nothing.

The office is just as it's always been. Neat stacks of paper cover the surface of Gaster's stone slab of a desk, while statuettes of unfamiliar monsters gaze down at you from their positions on the shelves around the room. Any shelf space that wasn't taken by those statuettes was filled instead by rows of the uniform black spines of Gaster's journals. Save for the couch with yellow cushions backed against one wall, there's nothing else of interest at all in this room.

You tread carefully as you step forward, as if you were walking into a museum. Maybe that's what this office is now anyway. A museum preserving a small part of what had been the illustrious Dr. Gaster's life -

You shake your head and clear your thoughts. Your uncle isn't gone. There's hope yet to find him. Now, where's Sans?

You turn back to the door. Maybe he'd gone even deeper into the lab, into the areas you'd never been allowed into. Even with you as Captain of the Guard, Gaster had been adamant that the furthest you go was the administrative area. 

Movement catches your eye, coupled with a flash of white. You whirl around just in time to spot a…a dog? The dog from the elevator earlier today? It stands on one of the stacks of paper, and just as you reach out and call to it, it turns around and leaps right off.

Paper flies everywhere, accompanied by a flurry of magic. Without thinking, you raise a gloved hand to eye level - and immediately paper slaps against it. You flinch away as unfamiliar magic spreads through your glove before simply dispersing on its own when you attempt to shake it off. It isn't as strong as the magic that had shielded Papyrus.

When you look back up, the dog is on the desk again, and the entire floor is covered in paper.

"Hold it right there - "

The dog doesn't give you a chance to finish, leaping off the desk. You lunge for it in an attempt to catch it, but, to your surprise, the dog changes direction in mid air and lands by the door instead. It barks once, then rushes out through it. You barely avoid crashing into the desk, using your momentum to spin yourself around and follow it out.

It leads you back the way you came, barking as it runs, before coming to a halt in front of the black door.

You stop, immediately distracted by the door ahead itself, because it _isn't_ black. Instead, the door is a strange, plain gray and,most curiously, you can feel magic emanating from it.

The dog's barks grow louder, drawing your attention. It stands right in the center of the corridor, barking as if it were taunting you. You frown and step forward, keeping a slow pace so as not to startle it.

You manage three steps before the dog stops barking and runs backward right into the door, disappearing into it as if either were made of water. You stand there frozen, trying to make sense of the sight.

Carefully, you reach out and touch the doorknob. Magic clasps around your hand, the door slams open and, as if the magic had taken the form of some invisible hand, you find yourself pulled forward through the doorway -

You are standing in a long corridor that stretches onward endlessly. White walls stand on either side, and an odd light with no discernible source seems to make everything exceptionally bright. It smells of nothing, much like the Core. 

There is no sign of the dog at all, and checking behind you reveals only a blank but solid wall.

Where the heck is this? Are you even still in the lab? You're certain you've never seen anything like this corridor in all the Underground before.

You start to walk, keeping your gaze on the distant white light ahead. Would you find Uncle Gaster here? Or maybe Papyrus's -

"Hey buddy." A low voice rings out behind you. "Why don't you turn around and shake my hand?"

You whirl around to find a skeleton standing there, one hand shoved into the pocket of his lab coat, the other held out to you. The white of his skull and that of his coat are near blinding in this place.

You look down at his outstretched hand, before returning your gaze to his face as you take his hand. It would've been impolite otherwise, and you're pleased to find that no external magic attempts to touch you this time.

"I'm Sans the skeleton," he says. He releases your hand, but he keeps his own poised in the air. Those pinprick lights in his dark eye sockets stay raised toward your face. It's as if he's waiting for some sort of reaction from you.

"I'm Captain Frisk Dreemurr," you say as you withdraw your hand, unsure what exactly he's after. "I've been looking for you, Sans the skeleton."

"Oh, really?" A hint of excitement laces his tone, much to your surprise. "What's the royal human need with me, huh?"

Royal human? Now there's a term you haven't heard in quite some time. You keep your expression neutral. "I promised Papyrus I'd come look for you."

His smile falters, like he'd expected something else. You study his expression for some hint to what that is exactly, but his face is unreadable to you.

"Guess I _should_ be heading back." He shoves his hand back into a pocket and turns away from you, and somehow you get the feeling that there's more meaning to this action than you can see. "I sure kept him waiting a while, huh. Must be bored by now."

"Actually, he's with my brother."

Your words give him pause, as he turns his head to eye you. "What's the prince doing with my brother?"

You grin. "Learning how to be cool."

That earns you his full attention, as he faces you now. His gaze flickers up and down twice before he speaks again. "Sounds like Paps’ work all right. I'm guessing they're out of the lab."

"That's correct. Your brother's safe with mine."

He starts to laugh, a low sound that fills the air and seems to make the corridor a lot more welcoming. You find yourself oddly comfortable with his presence now, as if you're...old friends, perhaps.

There are more important matters at hand. You wait for his laughter to die down before asking, "So, Sans, you wouldn't happen to know where Dr. Gaster is, would you?"

His initial grin returns in full force, and you're starting to think that's his default expression. Then he sighs and steps forward.

"Come with me a sec." He starts to walk, and you step aside briefly to let him past you before falling into step behind him.

"Where does this corridor lead?" you ask.

"Funny you should ask, that's pretty much what I was checking out when you showed up."

"And?"

He stops in his tracks, so suddenly that you nearly walk right into him. The silence stretches on, until you step closer to place a hand on his shoulder -

You freeze. He'd spoken too quickly for you to catch his exact words, but the _way_ he'd spoken is not lost on you. He had used that same, lilting and accented tone that your uncle uses when speaking Filipino.

"...sorry, what was that?" You venture the question, trying to determine if it had just been your imagination. You're certain it wasn't, but Gaster is the only person you've ever known to speak that way.

He starts walking again, prompting you to follow. When he speaks, it's in his usual tone. "We're in the Core."

That's not possible. You stare at the back of his head, trying to make sense of this, and find that you can't. You were in the lab, now you're in the Core.

"And Dr. Gaster?" You settle for going back to your original question, deciding for now that maybe Sans is lying for some unknown reason. You can't have suddenly teleported to the Core, can you?

"I've been looking for him." There's an edge to his tone now. "Y'know, he kicked us out of the lab."

You wonder if he's still wearing that grin. "You and Papyrus?"

"Yeah. Just up and kicked us out. Called us down to his office then shoved us through one of his magic portals." His pace remains steady as he walks, but you think you see his shoulders tense. "We woke up halfway across Hotland just in time to watch the lab blow up."

"He knew that the lab would explode." Your mind starts to race. Was the explosion not an accident after all? Or did Gaster simply sense the oncoming danger…?

"I think he blew himself up, actually."

You frown. "That's assuming an awful lot about matters we don't know -"

"No, you didn't see him. He definitely did this himself." Sans stops and turns around to face you, and his grin is still intact. You wonder if someone who knows him better would be able to pick up on more than just the grin.

"Then why?"

"Hell if I know," he snaps. "Dad was raving about the Core the entire time."

The Core - wait, _dad?_

"You and Papyrus are -"

"Gaster's kids," he finishes for you. "Yeah, we get that a lot."

So it must have been Gaster who set a protective field around Papyrus, and this is why Sans could speak just like him. They're his sons, and it seems much more obvious to you now that you've learned this.

It's a little odd though, that you never knew of them.

"Can you track him…" The question dies on your lips before you can finish it, as something odd catches your nose and your eye. That scent of burnt things has returned, and the corridor behind Sans is gone, replaced by a solid silver wall.

You look around, and realize you're back in the room where you found Asriel with Papyrus.

"Been trying that." Sans answers your unfinished question without any change in tone or demeanor. "If he doesn't wanna be found, then we aren't finding him."

"Then he's still alive." You settle your attention on the administrative area door, striding over to it as you speak. You can feel Sans' gaze on you. "How are we back here?"

The door opens easily enough when you try it, with no indication of the magic from earlier. Nothing happens when you touch it. You turn back to Sans, only to find that he'd followed you and is standing much too close for comfort.

"We took a shortcut."

So, magic then. You don't know why you expected any other answer.

"We've kept our brothers waiting long enough, I think." You step around Sans and make for the open doorway that leads back outside. "You've made it clear to me that Gaster is no longer here, and has likely gone into hiding."

"Sounds about right."

This time you hear him following you, footsteps loud against the gray tiled floor. You lead him toward the broken machine. "You've been awfully nonchalant about your father being missing. Can you be sure he isn't dust?"

Sans doesn't answer for a long while, but the question lingers over the two of you as you walk. It's only as you pass the large broken machine that you hear his footsteps stop. A glance back reveals that he's standing in front of it, just as you did earlier in that very same spot.

"Dad was always...weird. He talked about dreams a lot, when he wasn't talking about souls." His voice cracks, all too suddenly. Bewildered, you start toward him, even as he keeps talking. "He used to pick me up when I was a kid - I was even smaller than Paps, heh...anyway he used to do that and he'd tell me…"

He trails off. You reach a hand out to touch him, only for a certain familiar magic to repel you. You stare at the back of his head, unable to do any sort of comforting action you can think of. Maybe you shouldn't have asked after all. 

"Sans, I'm sorry - "

"C'mon." He moves away from the machine now, reaching up to gently push your hand away when he passes by you. His tone is back to normal, his grin still there. "Like you said, we've kept our bros waiting long enough."

"There might be other monsters here still."

"You'd hear them if there were."

You follow him in silence after that, back through the lab. He becomes talkative now, pointing out a variety of things to you as you pass them by. Here, the couch he'd fallen asleep on many times over the years, there the boxes he and Papyrus played hide and seek among. In this room, they'd practiced their magic. In that one Gaster taught him simple experiments to try. Eventually, Sans steps out onto Hotland soil. You linger behind him at the doorway, a single question that perhaps isn't the most important one to ask right now, but one you can't help but mull over repeatedly.

If Sans had spent so much time in the lab over the years, then how is it that you've never encountered him before?

The brothers are swiftly reunited, just as you are with yours.

"They're Gaster's sons," you tell him, watching the skeletons pull apart to start bantering. Asriel looks down to you, lifting a brow at the information you'd just given him.

"No way," he says, looking back to the pair, then back to you. "How come we've never met them before?"

A small laugh escapes you. "That's what I'd like to know myself."

"Explains the weird Filipino though."

You stop, and look up at him, hearing again in your head the way Sans' tone had shifted, had sounded just like Gaster for a single moment. "Papyrus can talk like Gaster too, huh."

"And I take it Sans pulled the creepy Gaster talk on you too." Asriel makes a face. He'd always found your uncle's speech weird, even as he'd stayed right there beside you while Gaster carried out his lessons.

"It's not _that_ creepy."

"Okay. I guess it was kinda cute when Papyrus did it."

"Thought so - "

You find yourself cut off, when Papyrus chooses exactly that moment to stride up to you. In the warm red light out here, the general shape of his face seems kinder, softer, than it had been in the harsh lights of the lab.

"Captain Frisk Dreemurr," he starts.

"Just Frisk will do, Papyrus," you tell him, but he shakes his head and continues on as if you hadn't said that.

You pause at his thanks. It isn't that big of a deal, is it? Sans hadn't even been the one you'd really been trying to find. But the brilliant smile on Papyrus's face tells you that it had very much been a bigger deal to him than he'd let on. You spare yourself a few seconds to choose your words before speaking.

"That's what the Royal Guard is for, Papyrus," you say, returning his smile with one of your own. "We're here to help _every_ monster."

" _Every_ monster?" Those tiny eyesockets of his are wide and gazing at you with something you suppose could be admiration. You think that's it, since it's similar to the one the armless child had worn.

It's a little embarrassing.

"Well, yes." You crouch so you're eye(socket) level with him, and in turn you feel his gaze become all the more intense. "Every and any monster, but especially those in need, who can't help themselves, who can't protect themselves. Of course, we have to listen to the King, but helping every monster is what the King wants anyway."

A thoughtful expression comes over him. You don't think you've ever seen a child this deep in thought before, but with his attention occupied for the moment, you glance around at the others. Sans is standing a good ways off, on the path that leads to the great elevator. Asriel is still standing beside you, looking rather pleased with your talking to Papyrus. Doge has wandered away, toward the lab, head raised to it.

"Let's talk while we walk, Papyrus," you say, and once the skeleton nods, you suggest to the others that you should return to the apartment building between New Home and Hotland. To your surprise, Doge volunteers herself to stay behind and guard the lab entrance, to make sure no one enters without permission. 

Your short trip back to the apartment building is filled with answering Papyrus's seemingly endless questions about the Royal Guard. You think he might make for a fine guard one day.

"What do you mean, we can't go to the lab?"

Suffice to say, 01's cousin is not taking the news well.

"There was an accident. We've closed everything off for investigative purposes." You find that you suddenly don't quite care if your impatience slips into your tone. You have a number of other things you need to do right now, primarily personally getting word to the King and Queen about the situation, as well as having news broadcasted about the laboratory (and perhaps, a good part of Hotland) being off limits for a while.

"We'll go around the accident then." She's certainly proving herself to be quite stubborn. "Head straight for the lab. This field trip is already behind schedule, a little detour wouldn't make any difference."

You shake your head. "You misunderstand. The accident was in the lab itself. Even if we were to allow you to go there, you'll find nothing that'll interest the children."

"Yeah," adds Asriel, "It kinda blew up."

"Wait, you mean, like, that sound earlier - " starts 01, finally speaking up, but he's cut off when the teacher gasps and her hands cover her mouth.

You glance at Asriel, frowning in his direction. You hadn't been sure yet if you'd wanted to tell her that exact bit of information. He notices you looking at him, and shrugs ever so discreetly.

" _Diyos ko_ ," whispers the teacher, catching your attention just as she says it again louder, "My god."

"Wh-what's wrong, cuz?" asks 01. He places a hand on her shoulder.

"I...we...if lunch hadn't been delayed..." She inhales, deeply, and lowers her hands to clutch her chest. "We would have been at the lab. When it - _Diyos ko_...the _kids_..."

You grimace, and turn to 01. "Take her back to the cafeteria, would you? See to it the kids don't learn what exactly happened for now."

He nods, and ushers her off, leaving you and Asriel in the now empty lobby.

"Asriel," you start, but he shakes his head.

"I didn't want to just leave, but, uh." He gives you a sheepish look, reaching up to rub the back of his neck. "I really need to head back to the spiders."

"You weren't done with your meeting?" you ask, then a certain other thing occurs to you. "Where's Porin? They could have helped Doge."

"Well I had to leave _something_ behind so the spiders would believe that I’d go back right away.”

You can’t help but feel uncomfortable with that. As much as you believe the spiders aren’t going to hurt one of your guards, you still have to wonder if Porin themself is all right with this.

Asriel picks up on the reason for your frown. “Hey, she volunteered.”

“Guess I’m giving them...her a day off soon,” you say. As you speak, you notice out the corner of your eye that the doors to the Core have opened. One of the rock monster scientists from the control center stumbles through, and you might not have given them much thought if not for the sheer distress simply emanating off them. You turn away from Asriel as the scientist hurries over to you.

“Oh thank god, Captain, you’re still here - “ The scientist turns their head to Asriel suddenly, as if just noticing him. “And the Prince too! Oh, oh thank goodness -”

“Woah, hey, what happened?” Asriel asks before you can.

“It's - it’s Dr. Gaster,” they stammer out, “Security footage of him - please, we need to show the King and Queen -”

You share another look with Asriel, and get back to work.

King Asgore and Queen Toriel arrive in the control center without much fanfare. You stand to greet them, and while they smile and greet you back with cheery tones, you’re fairly certain they can easily tell how shaken you are.

You aren’t really trying to hide it, anyway. The unease is plain on your face as you answer their questions and brief them on the situation with the lab as you lead them to one of the terminals in the center of the room. Two scientists stand there waiting for you, and they’re quick to exchange pleasantries with Asgore and Toriel before one of them, the one who’d handed you the Core’s reports just this morning, takes a seat and draws up the first video onto the screen.

It’s the corridor where you met Sans.

The scientist swivels around in his chair, and he’s about to speak when you hear the door behind you open again. You can easily guess who’s come in, but you don’t turn to look.

“Sorry for - taking a while.” It’s Asriel all right, sounding a little out of breath. “The spiders agreed to moving the meeting to next week - howdy mom, howdy dad.”

“You seem to be doing well with them.” Toriel must be smiling, and you can hear the pride in her voice.

“They certainly like you if they’re willing to postpone,” adds Asgore. You hear Asriel laugh softly, then feel a hand on your shoulder. A glance up tells you that your father has reached over to pat you. “Of course, we can discuss the spiders later. We’re here for another matter, yes?”

You nod and turn to face them. “After the lab exploded earlier, Dr. Gaster went missing. Not even his sons could tell us where he went.”

“Gaster has sons?” asks Asgore, surprise plain on his face.

“How odd,” says Toriel, expression mirroring her husband’s. “He never introduced us.”

“Wait,” the scientist speaks up, “ _We_ didn't know about them either!”

Well, isn't that strange. Sans had said he was around your age, so the fact that not even your parents or the very monsters who work with Gaster know he's the latter’s son makes you suspect something odd is going on here. This isn't why you called them here though.

“Ahem, in any case.” You gesture to the screen. “Even though he'd gone missing, the staff of the Core found this series of videos that...um, clears up his fate for us.”

“His fate?” asks Asriel. “Is Uncle Gaster _dead?_ ”

“Worse, I'm afraid,” answers the scientist. “Here, I'll show you. The timestamp on this is several minutes before the explosion.”

He taps a button, and you watch once more as Gaster appears in the corridor, right where you had earlier. Even with your gaze trained on the screen, you can feel your family step closer to get a better look.

“This corridor wasn't part of the original plans for the Core,” he continues, as the Gaster on the screen looks around. “But Dr. Gaster insisted on having it built. For security reasons we had to install cameras along it, but since it's essentially a dead end with no particular function, we tend to keep the cameras off.”

“Then the cameras came on just for this.” Toriel points to the screen, where Gaster has started to run. The screen starts to play through several videos, each from a camera from along the long, long corridor. Together, they presented a clear view of the Royal Scientist racing down the corridor.

“It might be the cameras reacted to Gaster’s magic,” you say.

“Each camera only turned on _as_ he passed by them,” says the scientist, “As with most of the Core tech, they’re capable of using extraneous monster magic as a power source…”

No one comments to him that all of you already know this. Instead, Asgore asks, “What _is_ he doing?”

“He's, well, accelerating, sir.” The scientist speeds through the rest of the videos, showing that Gaster had, indeed gone faster and faster as he raced down the corridor. Then he pulls up the last video, a seemingly static top down shot of what appeared to be the very center of the Core.

“And here is what we can assume is the reason,” you say, even as you feel your mouth turn dry at the sight of Gaster bursting into the room through one of the doors. Quietly you will him to stop, for the recorded past to change, but no such thing happens. Instead, you watch once again as glass appears beneath Gaster’s feet when he runs over empty air, only for him to slip right through it. 

He plummets, turning into a black pinprick against the blinding white of the abyss beneath the Core. Beside you, Asriel gasps in horror, and you hear Toriel sucking in a breath. Asgore remains completely silent.

“What can we do?” Asgore’s voice trembles as he speaks.

“...I don't know,” admits the scientist. “We don't know what's in the abyss, just that it can power the Core.”

"Would it be possible to send someone after him? Disable the glass and go down there to find him.” You'd been mulling it over since your first viewing of the videos. You spot both your parents nodding in agreement out the corner of your eye.

"I’m afraid it would be pointless," replies the scientist. "Here, I, ah, should have mentioned this earlier I suppose.” He rewinds the last video before playing it again. Once more, you watch as Gaster speeds into the room, but at a slower rate.

"Huh," mumbles Asriel from right beside you, too softly for anyone else to hear, "So now we're watching a slowed down vid of Uncle Gaster become Uncle Faster..."

You jab him with an elbow for that comment, earning yourself a quiet "ow".

"There." The scientist pauses the video once Gaster is but a dot on the screen. "Watch this carefully."

He plays it again, and you watch, with dull horror, as Gaster dissolves into dust rather than being enveloped by the abyss like you’d first assumed. His dust visibly scatters about the interior, before swirling together and turning black and then dropping into the depths below.

You bite your lip. Even though the video isn't playing again, the sight of Gaster's remains whirling about stays clear in your mind.

"I'm gonna be sick," says Asriel, and a glance at him tells you that he's stepped away, shaking his head. Toriel likewise moves, reaching for her son to comfort him, her own expression stony. Asgore stares straight at the screen, face unreadable save for his small frown.

You look back at the screen, staring at where Gaster had broken into dust.

"What the hell."

You jump.

When you've calmed yourself, you glance beside you, and find none other than Sans standing there, eyesockets dark and head raised in the direction of the screen.

How long has he been here? You reach toward him, gently placing a hand on his shoulder, and find no magic to repel you. 

Of course. Gaster is dead. No, worse. He's dead and completely lost to everyone.

“Sans - “ you whisper, but he reaches up and pulls your hand off himself.

“I told you,” he says, never looking at you. “Dad did this to himself.”

You shudder, and glance back to your family. Asgore hasn't moved yet, but fat tears roll down his cheeks. Toriel and Asriel are holding each other, the latter’s face buried in his mother’s shoulder. You can't even begin to imagine losing one of them to their own hand, and most especially not your father.

You turn back to Sans, but find that he is no longer there.

You move to join your family.

**Notes for the Chapter:**

> What lengths will I go to just to make [a](http://imgur.com/a/EkwlF) [joke](http://goo.gl/mlNs46) work seriously in my fics.
> 
> Also a reminder this fic has [an ask+rp blog](http://mercystick.tumblr.com) associated with it!


	3. Rebooted!

**Notes for the Chapter:**

> Hey everyone. I know how much it sucks to get an author's note rather than an update, but! The good news is that this AU isn't completely abandoned. I actually decided to simply reboot it as a comic, rather than struggling through writer's block and posting chapters that I'm not very happy with. I've come to take this fanfic as a learning experience in my limitations so while the comic will still definitely follow the same story, I believe it'll be much tighter and less all over the place.
> 
> You can head on over to the comic blog with this link: <https://bprk-comic.tumblr.com/>!

[](https://bprk-comic.tumblr.com/)


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